Liquid crystal display device and method of repairing bad pixels therein

ABSTRACT

A liquid crystal display device and a method of repairing bad pixels thereof, in which the bad pixels can be efficiently and easily repaired, includes a first insulating substrate, a gate wiring and a storage wiring arranged substantially parallel to each other in a first direction on the first insulating substrate, a data wiring intersecting the gate and storage wirings in an insulated manner and arranged substantially in a second direction, and a pixel electrode formed on a pixel area defined by the gate and data wirings. The storage wiring includes a horizontal portion arranged substantially in the first direction and at least a part of which does not overlap the pixel electrode, and a vertical portion branching off substantially in the second direction from the horizontal portion and overlapping the data wiring.

CROSS REFERENCE

This patent application is a Continuation application of U.S.application Ser. No. 14/606,941 filed Jan. 27, 2015, which is acontinuation of U.S. application Ser. No. 13/844,256 filed Mar. 15,2013, which is a continuation of U.S. application Ser. No. 13/224,150filed Sep. 1, 2011 (now U.S. Pat. No. 8,400,609), which is acontinuation of U.S. application Ser. No. 12/534,537 filed Aug. 3, 2009(now U.S. Pat. No. 8,045,075), which is a continuation of U.S.application Ser. No. 11/934,656 filed Nov. 2, 2007 (now U.S. Pat. No.7,580,108), which application claims priority from Korean PatentApplication No. 10-2006-0108410 filed on Nov. 3, 2006 in the KoreanIntellectual Property Office, the disclosures of which are incorporatedherein by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to an image display device and, moreparticularly, to a liquid crystal display device and a method ofrepairing bad pixels therein.

2. Description of the Prior Art

The cathode ray tube (CRT), liquid crystal display (LCD), plasma displaypanel (PDP) apparatus, electronic paper display (EPD), and so forth areexamples of commonly used image display devices that are being developedto the meet demand for miniaturization, weight reduction, and low powerconsumption.

A liquid crystal display includes a color filter substrate having acolor filter, a thin film transistor (“TFT”) substrate having a TFTarray, and a liquid crystal layer interposed between the color filtersubstrate and the TFT substrate.

The TFT substrate of the LCD includes a plurality of gate lines, aplurality of storage wirings, a plurality of data lines, a pixelelectrode and others. There is a concern that an open may occur in theindividual wirings or a that a short between the wirings may occur. Ifone data line is opened, all pixels in a column connected to that dataline will not operate.

When pixel defects occur, a process of repairing the pixel defects isgenerally performed, but the process may give rise to further pixeldefects, for example, a short between wirings overlapping each other. Assuch, a method is needed that efficiently and easily repairs bad pixelswithout causing any other pixel defects.

SUMMARY

Accordingly, to an aspect of the present invention ran exemplaryembodiment provides an LCD device where bad pixels to be efficiently andeasily repaired.

The exemplary embodiments of the present invention further provide amethod of repairing bad pixels in such an LCD device.

In an exemplary embodiment a liquid crystal display device includes: afirst insulating substrate; a gate wiring and a storage wiring arrangedsubstantially parallel to each other in a first direction on the firstinsulating substrate; a data wiring intersecting the gate and storagewirings in an insulated manner, and arranged substantially in a seconddirection; and a pixel electrode formed on a pixel area defined by thegate and data wirings, wherein the storage wiring includes a horizontalportion arranged substantially in the first direction and at least apart of which does not overlap the pixel electrode, and a verticalportion branching off substantially in the second direction from thehorizontal portion and overlapping the data wiring.

In accordance with another exemplary embodiment, a method of repairingbad pixels of a liquid crystal display device comprises: providing thethin film transistor substrate having gate wiring and a storage wiringarranged substantially parallel to each other in a first direction on aninsulating substrate, data wiring intersecting but insulated from thegate and storage wirings and arranged substantially in a seconddirection, a pixel electrode formed on a pixel area defined by the gateand data wirings,

wherein the storage wiring comprises a horizontal portion arrangedsubstantially in the first direction and at least a part of which doesnot overlap the pixel electrode, and a vertical portion branching offsubstantially in the second direction from the horizontal portion andoverlapping the data wiring; and cutting the storage wiring byirradiating a laser beam onto a part of the horizontal portion that doesnot overlap the pixel electrode.

BRIEF DESCRIPTION

The above and other objects, features and advantages of the presentinvention will be apparent from the following detailed description takenin conjunction with the accompanying drawings, in which:

FIG. 1 is a layout view of a TFT substrate included in an LCD device inaccordance with a first preferred embodiment of the present invention;

FIG. 2 is a sectional view taken along line A-A′ of FIG. 1;

FIG. 3 is a layout view of a color filter substrate included in the LCDdevice in accordance with the first preferred embodiment of the presentinvention;

FIG. 4 is a layout view of the LCD device in accordance with the firstpreferred embodiment of the present invention;

FIG. 5 is a sectional view taken along line B-B′ of FIG. 4;

FIG. 6 is a view schematically illustrating a method of repairing anopen when an open occurs in a data line of the TFT substrate of FIG. 1;

FIG. 7 is a view schematically illustrating a method of repairing ashort when the short occurs in a data line of the TFT substrate of FIG.1;

FIG. 8 is view schematically illustrating a method of repairing a shortwhen the short occurs in a pixel electrode of the TFT substrate of FIG.1;

FIG. 9 is a layout view of a TFT substrate included in an LCD device inaccordance with a second preferred embodiment of the present invention;

FIG. 10 is a sectional view taken along line C-C′ of FIG. 9;

FIG. 11 is a view schematically illustrating a method of repairing anopen when the open occurs in a data line of the TFT substrate of FIG. 9;

FIG. 12 is a view schematically illustrating a method of repairing ashort when the short occurs in a data line of the TFT substrate of FIG.9;

FIG. 13 is view schematically illustrating a method of repairing a shortwhen the short occurs in a pixel electrode of the TFT substrate of FIG.9; and

FIG. 14 is a view schematically illustrating how a bridge electrodefunctions when a short occurs in a storage wiring of the TFT substrateof FIG. 9.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

It should be noted that the term “on”, as mentioned herein, is used notonly in the case where elements or layers are directly on other elementsor layers, but also in the case where other intermediate elements orlayers intervene therebetween. In contrast, the term “directly on”, asmentioned herein, means that elements or layers are on other elements orlayers without any other intermediate elements or layers interveningtherebetween. Like numbers designate like elements throughout thespecification and drawings.

Spatially relative terms such as “below”, “beneath”, “lower”, “above”and “upper” may be used herein for easily describing correlationsbetween one element or constituents and other elements or constituents,as illustrated in the figures. It should be appreciated that thespatially relative terms are intended to encompass differentorientations of the element in use or operation in addition to theorientation depicted in the figures. Like numbers designate likeelements throughout the specification and drawings.

Reference will now be made to a first preferred embodiment of thepresent invention with reference to FIGS. 1 to 5. FIG. 1 illustrates thelayout of a TFT substrate included in an LCD device according to thefirst embodiment of the present invention. FIG. 2 illustrates a sectiontaken along line A-A′ of FIG. 1. FIG. 2 illustrates the layout of acolor filter substrate included in the LCD device according to the firstembodiment of the present invention. Finally, FIG. 5 illustrates asection taken along line B-B′ of FIG. 4.

As illustrated in FIGS. 4 and 5, the LCD device according to the firstembodiment of the present invention includes a TFT substrate, a colorfilter substrate opposite thereto, and a liquid crystal layer 3 formedbetween these two substrates, and oriented in a certain direction.

First, a detailed description of the TFT substrate will be given withreference to FIGS. 1 and 2.

The TFT substrate according to the first embodiment of the presentinvention includes a gate wiring 22 and 24, a storage wiring 28 and 29,a gate insulating film 30, an active layer 40, an ohmic contact layer55, 56, a data wiring 62, 65, 66, and 67, a protective film 70, a pixelelectrode 82 and the like, all of which are formed on a first insulatingsubstrate 10.

The first insulation substrate 10 may be made of heat-resistant,optically transparent material such as transparent glass or plastic.

The gate wiring 22 and 24 and the storage wiring 28 and 29 are formed onthe first insulating substrate 10, and are arranged substantiallyparallel to each other in a first direction. The gate wiring 22 and 24and the storage wiring 28 and 29 may be formed on the same layer, forexample, on the first insulating layer 10.

The gate wiring 22 and 24 includes a gate line 22 and a gate electrode24. The gate line 22 is arranged substantially in the first direction,for example, in a transverse direction, and transmits a gate signal. Thegate electrode 24 projects from the gate line 22 in the form of aprotrusion and constitutes three terminals of a TFT, together with asource electrode 65 and a drain electrode 66, as will be describedbelow.

The storage wiring 28 and 29 includes a horizontal portion 28 and avertical portion 29. The horizontal portion is arranged substantiallyparallel to the gate wiring 22 and 24 in the first direction. Thevertical portion 29 branches off substantially in a second direction andoverlaps the data wiring 62, 65, 66, and 67, as will be described below.

A storage voltage is applied to the storage wiring 28 and 29, whichforms a storage capacitor together with the pixel electrode 82, as willbe described below. In accordance with an aspect of the invention, thestorage wiring 28 and 29 also functions to repair pixel defects.

The horizontal portion 28 is arranged parallel to and spaced from thegate wiring 22 and 24, and in particular, the gate line 22. Thehorizontal portion 28 is disposed to overlap the pixel electrode 82, aswill be described below, and thus the storage capacitor is formedbetween the pixel electrode 82 and the horizontal portion 28.

At least apart of the horizontal portion 28 does not overlap the pixelelectrode 82. Specifically, the horizontal portion 28 is generallyparallel to the gate line 22, but a bent portion 28 a projecting beyondan edge of the pixel electrode 82 is formed in a part of the horizontalportion 28 such that the part of the horizontal portion 28 does notoverlap the pixel electrode 82. The bent portion 28 a is bent toward thegate line 24 adjacent to the horizontal portion 28, but does not overlapthe gate wiring 22 and 24, and the data wiring 62, 65, 66, and 67.Although the bent portion 28 a is U-shaped in the present embodiment, itmay take other shapes such as a circular arc shape, a ridge shape, andothers, so long as it does not overlap the pixel electrode 82. Variousmodifications may be made to its shape. In this way, since the storagewiring 22, 24 includes the bent portion 28 a not overlapping the pixelelectrode 82, it is possible to efficiently repair an open or a shortwhen the open or the short occurs in the data line 62 and the pixelelectrode. Such a method of repairing bad pixels of the LCD device willbe described in detail in the following.

From the above-mentioned horizontal portion 28, the vertical portion 29branches off substantially in a second direction, for example, in alongitudinal direction. Specifically, the horizontal portion 28 may bearranged parallel to and along the long side of the TFT substrate in atransverse direction, and a plurality of vertical portions 29 may branchoff from each horizontal portion 28 and be arranged parallel to theshort side of the TFT substrate in a longitudinal direction.

The vertical portion 29 branches off from the horizontal portion 28, andis formed in such a manner that the distal end of the vertical portion29 adjoins the gate line 22 of an adjacent pixel, but is spaced from thegate line 22 of the adjacent pixel such that it is not electricallyconnected thereto.

The vertical portion 29 overlaps the data line 62 as will be describedbelow, and is used for repairing an open or a short of the data line 62.A description thereof will also be given to explain a method ofrepairing bad pixels of the LCD device according to the presentembodiment.

The vertical portion 29 is so formed as to have a wider width W₁ thanthe width W₂ of the data line 62, which facilitates repair of the dataline 62. Edges of the vertical portion 29 overlap the pixel electrode 82along the second direction, for example, along a longitudinal direction,thereby preventing light emitted from a backlight assembly (not shown)from leaking. That is, the vertical portion 29 overlaps a pair of pixelelectrodes 82 adjacent to each other. Further, referring to FIG. 3, thevertical portion 29 has the same width W₁ as the width W₃ of a blackmatrix 120, so as not to reduce an aperture ratio.

Referring to FIGS. 1 and 2 again, the gate wiring 22 and 24 and thestorage wiring 28, may be made of an aluminum-based metal such asaluminum (Al) or an aluminum alloy, a silver-based metal such as silver(Ag) or a silver alloy, a copper-based metal such as copper (Cu) or acopper alloy, a molybdenum-based metal such as molybdenum (Mo) and amolybdenum alloy, chrome (Cr), titanium (Ti), Tantalum (Ta) or the like.Further, the gate wiring 22 and 24 and the storage wiring 28 and 29 mayhave a multilayer structure including two electrically conductive layers(not shown) which have different physical properties. In addition, thegate wiring 22 and 24 and the storage wiring 28 and 29 may be formed byapplying PEDOT (PolyEthyleneDiOxyThiophene), which is an electricallyconductive organic polymer material, in a coating method, or by printingthe same using an inject-printing method.

The gate insulating film 30, made of inorganic insulating material suchas silicone oxide (SiOx) or silicone nitride (SiNx), or organicinsulating material such as BCB (BenzoCycloButene), acrylic material orpolyamide, covers the gate wiring 22 and 24 and the storage wiring 28and 29 on the first insulating substrate 1.

The active layer 40, made of hydrogenated amorphous silicone,polycrystalline silicone or electrically conductive organic material, ispartially formed in an upper portion of the gate insulating film 30.

The active layer 40 may have various shapes including an island shapeand a linear shape. For example, when the active layer 40 is formed inthe shape of an island as in the present embodiment, it overlaps thegate electrode 24 on the gate electrode 24 and at least partiallyoverlaps the source electrode 65 and the drain electrode 66, as will bedescribed below. The shape of the active layer 40 is not limited to anisland shape, but can be many shapes. When the active layer is formed ina linear shape, it is positioned underneath the data line 62 and mayhave a shape extending up to above the gate electrode 24.

The ohmic contact layers 55, 56 may be formed on the active layer 40.The ohmic contact layers 55, 56 are made of n+ hydrogenated amorphoussilicone highly doped with n-type impurities, ITO material doped withp-type impurities, or others. The ohmic contact layers 55, 56 arepositioned in pairs on the active layer 40, thereby improving a contactcharacteristic between the active layer 40 and the source and drainelectrodes 65, 66 as will be described below. When the contactcharacteristic between the active layer 40 and the source and drainelectrodes 65, 66 formed thereon is good, the ohmic contact layers 55,56 may be omitted.

The data wiring 62, 65, 66, and 67 are formed on the active layer 40 andthe gate insulating film 30. The data wiring 62, 65, 66, and 67 isarranged substantially in the second direction, for example, in alongitudinal direction. The data wiring 62, 65, 66, and 67 includes adata line 62 intersecting the gate line 22 in an insulated manner tothereby define a pixel, the source electrode 65 branching off from thedata line 62 and extending up to above the active layer 40, and thedrain electrode 66 separated from and facing the source electrode 65.

The data line 62 is arranged in a longitudinal direction, intersects thegate line 22, and is applied with a data signal.

The source electrode 65 may branch off from the data line 62 along aJ-shaped path, and at least partially overlaps the active layer 40.

One end of the drain electrode 66 is positioned in a recessed portion ofthe J-shaped source electrode 65 and at least partially overlaps theactive layer 40.

An enlarged drain electrode portion 67, formed wider than the drainelectrode 66, extends from one end of the drain electrode 66, and iselectrically connected to the pixel electrode 82. The enlarged drainelectrode portion 67 is formed outside of a pixel area so as not toreduce an aperture ratio. In order to minimize the aperture ratio, aregion extending from one end of the drain electrode 66 to the enlargeddrain electrode portion 67 is formed in a linear shape and overlaps thehorizontal portion 28 of the storage wiring 28 and 29. The pixel arearefers to an area defined by the gate wiring 22 and 24 and the datawiring 62, 65, 66, and 67. The pixel area may be understood as an areathrough which light emitted from the backlight assembly passes. Thus,the color filter area (see reference numeral “130” in FIG. 3) of thecolor filter substrate (see reference numeral “2” in FIG. 5), whichcorresponds to the pixel area of the TFT substrate, may also beunderstood as a pixel area.

The data wiring 62, 65, 66, and 67 may be made of a refractory metalsuch as chrome, a molybdenum-based metal, tantalum and titanium, and mayalso have a multilayer structure consisting of, for example, a lowerlayer (not shown), which is formed of the refractory metal or the like,and an upper layer (not shown), which is formed of a low-resistivitymaterial and located on the lower layer. An example of the multilayerstructure includes a double layer of a lower chrome layer and an upperaluminum layer or a lower aluminum layer and an upper molybdenum layer,and a triple layer of molybdenum-aluminum-molybdenum layers.

The protective film 70 is formed on the data line 62, the drainelectrode 66 and an exposed semiconductor layer 40. The protective film70 is made of an inorganic material consisting of silicone nitride orsilicone oxide, an organic photosensitive material having a goodplanarization characteristic, a low-dielectric insulating material suchas a-Si:C:O and a-Si:O:F formed by plasma enhanced chemical vapordeposition (PECVD), or others. Further, the protective film 70 may havea double layer structure of a lower inorganic layer and an upper organiclayer in order to make the most of superior characteristics of theorganic layer, and simultaneously protect the exposed semiconductorlayer 40.

The protective film 70 is formed with a contact hole 72 through whichthe enlarged drain electrode portion 67 is exposed.

The pixel electrode 82 is formed on the protective film 70, and iselectrically connected to the drain electrode 66 through the contacthole 72. A drain-electrodes-connecting portion 82 a is formed on oneside of the pixel electrode 82. This portion 82 a is electricallyconnected to the drain electrode 66, in particular, to the enlargeddrain electrode portion 67 through the contact hole 72, and a datavoltage is applied thereto via the drain electrode 66. In order not toreduce the aperture ratio, the drain-electrode-connecting portion 82 amay project outside of the pixel area through which light emitted fromthe backlight assembly passes.

The pixel electrode 82 may be made of a transparent, electricallyconductive material such as ITO (Indium Tin Oxide) or IZO (Indium ZincOxide), or a reflective, electrically conductive material such asaluminum.

Referring to FIGS. 4 and 5, when a data voltage is applied to the pixelelectrode 82, the pixel electrode 82, together with a common electrode140 of the color filter substrate, generates an electric field, therebydetermining the orientation of liquid crystal molecules of the liquidcrystal layer 3.

Reference will now be made to the color filter substrate included in theLCD device according to the present embodiment with reference to FIGS. 3to 5.

The color filter substrate includes a black matrix 120, a color filter130, an overcoat film (not shown), a common electrode 140, and others,all of which are formed on the lower surface of a second insulatingsubstrate 100, and is disposed to face the TFT substrate.

The second insulating substrate 100 of the color filter substrate may bemade of heat-resistant, optically transparent material such astransparent glass or plastic.

The black matrix 120, made of an opaque material such as chrome, isformed on the insulating substrate according to the present embodimentto partition a pixel area.

The black matrix 120 is arranged in the shape of a matrix along firstand second directions, and its width W₃ in the second direction, forexample, in a longitudinal direction, is substantially the same as thatof the vertical portion 29 of the storage wiring 28 and 29, as statedabove.

The pixel area partitioned by the black matrix 120 is successivelyformed of red, green and blue color filters 130. The color filters 130are made of materials transmissive to light of different colors, andthus functions to transmit therethrough light of a specific wavelengthband.

The color filters 130 may be disposed in a stripe, mosaic or deltapattern, but stripe-patterned color filters 130 will be described by wayof example in the present embodiment. In the stripe-patterned colorfilters 130, color filters of the same color are disposed in the seconddirection, for example, in a longitudinal direction. That is, viewed inthe first direction, for example, in a transverse direction, an nth (nis an integer) color filter may be a red color filter, an (n+1)th colorfilter may be a green color filter, and an (n+2)th color filter may be ablue color filter.

The overcoat film is formed on the color filters 130. The commonelectrode 140, made of transparent, electrically conductive materialsuch as ITO or IZO, is formed on the overcoat film. Further, althoughnot shown in the drawings, a spacer for providing a definite gap betweenthe common electrode 140 and the TFT substrate may be formed on thepixel electrode 82, and the gap left by the spacer is filled with theliquid crystal layer 3.

Reference will now be made in detail to a method of repairing bad pixelswhen pixel defects occur in the LCD device, with reference to FIGS. 6 to8. FIG. 6 schematically illustrates a method of repairing an open whenthe open occurs in the data line of the TFT substrate in FIG. 1, FIG. 7schematically illustrates a method of repairing a short when the shortoccurs in the data line of the TFT substrate in FIG. 1, and FIG. 8schematically illustrates a method of repairing a short when the shortoccurs in the pixel electrode of the TFT substrate in FIG. 1.

Since the TFT substrate includes a plurality of wirings and a pluralityof electrodes, an open may occur in the individual wirings andelectrodes or a short may occur between the wirings or between thewirings and the electrodes.

Specifically, if an open region O₁ occurs in the data line 62, allpixels connected to the opened data line 62 will not operate.

In order to repair such pixel defects, a laser beam is irradiatedthrough the data line 62 and the storage wiring 28 and 29 correspondingto both sides of the open region O₁ to thereby form laser short regionsLS₁ and LS₂. The laser beam forms the laser short regions LS₁ and LS₂ bypartially melting the data line 62 and the storage wiring 28 and 29, andthus the data line 62 and the storage wiring 28 and 29 are electricallyconnected to each other. As a result of this, a signal applied throughthe data line 62 does not pass through the open region O₁, but aseparate current path, that is, a bypass to the vertical portion 29 ofthe storage wiring 28 and 29 via the laser short regions LS₁ and LS₂, isformed, so that bad pixels can be easily repaired. For example, a laserbeam belonging to a green wavelength band (about 532 nm) may be used inrepairing the pixel defects, and a laser beam with a power of 0.1 to 1mJ may be applied for melting the data line 62 and the vertical portion29 of the storage wiring 28 and 29. The diameter of the laser beam spotmay be ranged from 1 to 4 μm, for example.

However, if only the above-mentioned method step is performed, a datasignal applied through the data line 62 is transferred to the storagewiring 28 and 29, and thus interferes with a storage voltage signalapplied to the storage wiring 28 and 29, which may have a negativeinfluence on other good pixels. Thus, it is preferable to cut thestorage wiring 28 and 29 of the corresponding bad pixel. Specifically, alaser beam is irradiated onto a part not overlapping the pixel electrode82, that is, the bent portion 28 a, of the horizontal portion 28 of thestorage wiring 28 and 29 to thereby form laser cut regions LC₁ and LC₂,and thus the storage wiring 28 and 29 is cut. Here, all the bentportions 28 a of pixel areas adjacent to both sides of the cut data line62 are formed with the laser cut regions LC₁ and LC₂. That is, when onedata line 62 is opened, the laser cut regions LC₁ and LC₂, are formed intwo bent portions 28 a positioned on both sides of the cut data line 62.By cutting the part not overlapping the pixel electrode 82, that is, thebent portion 28 a, it is possible to prevent signal interference withother pixels, which may arise in the bad-pixel repair process.

In the present embodiment, by using a laser beam and providing thestorage wiring 28 and 29 with the bent portion 28 a not overlapping thepixel electrode 82, the above-mentioned signal interference due to ashort between the data line 62 and the source electrode 65 positionedthereunder or a further short of the very thin data line 62 can beprevented, as compared to a case where, in order to repair the open dataline 62, open portions of the data line 62 are connected to each otherby using CVD.

As illustrated in FIG. 7, since the overlapping area between the dataline 62 and the storage electrode 82 is large, they are highly likely tobe shorted by particles, etc. If a short region S₁ occurs between thedata line 62 and the storage wiring 28 and 29, all storage wiring 28 and29 connected to the shorted data line 62 are attacked by theabove-mentioned signal interference, which results in pixel defects.

In such a case, since the horizontal portion 28 of the storage wiring 28and 29 is formed with the bent portion 28 a projecting beyond an edge ofthe pixel electrode, laser cut regions LC₃ and LC₄ can be formed in thebent portions 28 a of pixel areas adjacent to both sides of the shorteddata line 62. That is, when one data line 62 is shorted, laser cutregions LC₃ and LC₄ are formed in two bent portions 28 a, positioned onboth sides of the shorted data line 62, respectively, thereby preventingsignal interference from occurring in the storage wiring 28 and 29 andthe data wiring 62, 65, 66, and 67.

In this way, when a short occurs between the data line 62 and thevertical portion 29 of the storage wiring 28 and 29, the TFT substrateaccording to the present embodiment enables the laser cut regions LC₃and LC₄ to be easily formed in the horizontal portion 28 of the storagewiring 28 and 29, which adjoins the short region SI, because the storagewiring 28 and 29 is formed with the bent portion 28 a projecting beyondan edge of the pixel electrode 82. Consequently, pixel defects caused bythe shorted data line can be easily repaired.

As illustrated in FIG. 8, if a short region S2 occurs between thestorage wiring 28 and 29 and the pixel electrode 82 by particles, etc.,an undesired storage voltage is applied to the pixel electrode 82,resulting in pixel defects.

In such a case, since the horizontal portion 28 of the storage wiring 28and 29 is formed with the bent portion 28 a projecting beyond an edge ofthe pixel electrode, laser cut regions LC₅ and LC₆ can be formed in thebent portions 28 a of pixel areas adjacent to both sides of the shortedstorage wiring 28 and 29. That is, when one storage wire is shorted,laser cut regions LC₅ and LC₆ are formed in two bent portions 28 a,positioned on both sides of the shorted data line 62, respectively.Thus, all pixels connected to the shorted storage wiring 28 and 29 canbe prevented from suffering from pixel defects.

In the TFT substrate according to the present embodiment, when a shortoccurs between the pixel electrode 82 and the storage wiring 28 and 29,the laser cut regions LC₅ and LC₆ can be easily formed in the storagewiring 28 and 29 because the storage wiring 28 and 29 is formed with thebent portion 28 a projecting beyond an edge of the pixel electrode 82.Consequently, all pixels connected to the shorted storage wiring 28 and29 can be prevented from suffering from pixel defects. In such abad-pixel-repair method, bad pixels can be repaired without turning offthe bad pixels by irradiating a laser beam onto the defective pixelelectrode 82 to generate a short between the pixel electrode 82 and thegate line 22.

Reference will now be made in detail to a second preferred embodiment ofthe present invention with reference to FIGS. 9 and 10. FIG. 9illustrates the layout of a TFT substrate included in an LCD deviceaccording to the second embodiment, and FIG. 10 illustrates a sectiontaken along line B-B′ of FIG. 9.

For explanatory convenience, the same functional constituents as thoseillustrated in the drawings of the previous embodiment are designated bythe same reference numerals, and thus a description thereof is brief oromitted. As illustrated in FIGS. 9 and 10, the LCD device according tothe present embodiment has essentially the same structure as that of theLCD device according to the previous embodiment of the presentinvention, except that the LCD device according to the presentembodiment further includes a bridge electrode 84 connecting the storagewiring 28 and 29 of adjacent pixels to each other.

In the present embodiment, a projection portion 29 a is formed at thedistal end of the vertical portion 29 of the storage wiring 28 and 29.The projection portion 29 a projects toward the pixel electrode 82′ andthus is positioned on a vertical line, together with the bent portion 28a of the storage wiring 28 and 29 of an adjacent pixel.

The bridge electrode 84 electrically connects a pair of storage wires 28and 29 neighboring with respect to the gate wiring 22 and 24.Specifically, the bridge electrode 84 electrically connects thehorizontal portion 28 of one of the pair of neighboring storage wiring28 and 29 to the vertical portion 29 of the other storage wiring 28 and29. The bridge electrode 84 electrically connects the bent portion 28 aand the projection portion 29 a of the storage wiring 28 and 29 to eachother through bridge electrode contact holes 74, 76. Thus, since thestorage wiring 28 and 29 are electrically connected to each other bymeans of the bridge electrode 84, other pixels can be prevented frombeing affected by signal delay even when any one of the storage wirings28 and 29 is cut in order to repair pixel defects. This will bedescribed in detail below.

The bridge electrode 84 is made of substantially the same material asthat of the pixel electrode 82′ adjacent to the bridge electrode 84, andthe bridge electrode 84 and the pixel electrode 82′ are formed insubstantially the same layer. Specifically, when the pixel electrode 82′is made of transparent, electrically conductive material such as ITO orIZO, the bridge electrode 84 is also formed as an ITO or IZO electrode.

The bridge electrode 84 may be formed in every pixel areas. That is, apixel area is defined as a red pixel area, a green pixel area or a bluepixel area according to the type of color filter (see reference numeral“130” in FIG. 3) corresponding thereto, and these pixel areas may beformed with the bridge electrode 84. The pixel electrode 82′ of thepixel area, in which the bridge electrode 84 is formed, may be narrowerthan the pixel electrode 82 of the pixel area where the bridge electrode84 is not formed. That is, in the pixel area where the bridge electrode84 is formed, the pixel electrode 82′ is spaced apart from the bridgeelectrode 84 by partially cutting a corner of the pixel electrode 82′,so as not to be electrically connected to the bridge electrode 84.

The bridge electrode 84 may be formed in all pixel areas, but it is alsopossible to form the bridge electrode 84 only in one or two pixelarea(s) of the red, green and blue pixel areas. Any one pixel area maybe the blue pixel area whose contribution to luminance is minimal Byforming the bridge electrode 84 in every blue pixel areas whosecontributions to luminance are minimal, luminance reduction according tothe formation of the bridge electrode 84 can be minimized, and reductionin an aperture ratio can be prevented from being caused by a spacer tobe formed in the color filter substrate because the spacer is formed ina portion corresponding to the bridge electrode 84.

Reference will now be made in detail to a method of repairing bad pixelswhen pixel defects occur in the LCD device according to the presentembodiment, with reference to FIGS. 11 to 14. FIG. 11 schematicallyillustrates a method of repairing an open when the open occurs in thedata line of the TFT substrate in FIG. 9, FIG. 12 schematicallyillustrates a method of repairing a short when the short occurs in thedata line of the TFT substrate in FIG. 9, FIG. 13 schematicallyillustrates a method of repairing a short when the short occurs in thepixel electrode of the TFT substrate in FIG. 9, and FIG. 14schematically illustrates how the bridge electrode functions when anopen occurs in the storage wiring of the LCD device in FIG. 9.

First, the TFT substrate, in which the bridge electrode 84 is formed, isas described in FIGS. 9 and 10.

As illustrated in FIG. 11, if an open region O₁′ occurs in the data line62, pixel defects occur. In order to repair such pixel defects, lasershort regions LS₁′, LS₂′ are formed by irradiating a laser beam onto thedata line 62 and the vertical portion 29 of the storage wiring 28 and 29corresponding to both sides of the open region O₁′, thereby electricallyconnecting the data line 62 and the storage wiring 28 and 29. Further,laser cut regions LC₁′, LC₂′ are formed by irradiating a laser beam ontothe bent portions 28 a of the storage wiring 28 and 29 adjacent to bothsides of the opened data line 62. Since the storage wiring 28 and 29,connected to each other in a transverse direction, are applied with thesame storage voltage, if the laser cut region LC1′ and LC2′ exists inthe storage wiring 28 and 29 of any one pixel area, the storage voltageof the storage wiring 28 and 29, connected to each other in the firstdirection, is not transferred to following pixel areas. However, thestorage wiring including the laser cut region LC1′ and LC2′ iselectrically connected to the storage wiring 28 and 29, which isdisposed in the very next row, by means of the bridge electrode 84, andthus is applied with a storage voltage signal from the storage wiring 28and 29 disposed in the next row. For this reason, all pixel areasconnected to the storage wiring 28 and 29, including the laser cutregion LC1′ and LC2′, can be prevented from being affected by signaldelay.

As illustrated in FIG. 12, if a short region S₁′ occurs between the dataline 62 and the storage wiring 28 and 29, all storage wiring 28 and 29connected to the shorted data line 62 are affected by signalinterference, which results in pixel defects.

In order to repair such pixel defects, laser cut regions LC₃′ and LC₄′are formed in two bent portions 28 a positioned on both sides of theshorted data line 62, respectively, thereby preventing signalinterference from occurring in the storage wiring 28 and 29 and the datawiring 62, 65, 66, and 67. If only the laser cut region LC₃′ and LC₄′exists in any one pixel area, signal delay does not occur in other pixelareas following that pixel area because the storage wirings 38, 39 areelectrically connected by means of the bridge electrode 84, which wasdescribed with reference to FIG. 1.

As illustrated in FIG. 13, if a short region S2′ occurs between thestorage wiring 28 and 29 and the pixel electrode 82′, laser cut regionsLC₅′, LC₆ are formed in the bent portions 28 a adjacent to both sides ofthe shorted storage wiring 28 and 29, respectively. If only the lasercut region LC₅′, LC₆ exists in any one pixel area, signal delay does notoccur in other pixel areas following that pixel area because the storagewirings 38, 39 are electrically connected by means of the bridgeelectrode 84, which was described with reference to FIG. 11.

As illustrated in FIG. 14, if an open region O₂′ occurs in the storagewiring 28 and 29, for example, the horizontal portion 28 thereof, signaldelay occurs in the pixel area where the open region O₂′ exists.However, since the storage wiring 28 and 29 of an nth row iselectrically connected to the storage wiring 28 and 29 of an (n+1)th rowby means of the bridge electrode 84, the storage voltage signal, appliedto the storage wiring 28 and 29 of the (n+1)th row, is transferred tothe storage wiring 28 and 29 of the nth row. Thus, whichever pixel areaof the nth row has an open region O₂′, signal delay, a phenomenon inwhich a storage signal is not transferred to other pixel areas of thesame row, cannot occur.

According to the present invention described above, at least one of thefollowing advantageous effects can be obtained:

First, even if bad pixels are caused by an open of the data line, thebad pixels can be securely and easily repaired using the bent portionand the bridge electrode of the storage wiring.

Second, even if bad pixels are caused by a short between the storagewiring and the data line or the pixel electrode, the bad pixels can besecurely and easily repaired using the bent portion and the bridgeelectrode of the storage wiring.

Last, even if the storage wiring is opened, the bridge electrodeelectrically connects the opened storage wiring to the storage wiringpositioned in a different row, and thus the opened storage wiring doesnot suffer from signal delay.

Although preferred embodiments of the present invention have beendescribed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the essential features and the scopeand spirit of the invention as disclosed in the accompanying claims.Therefore, it should be appreciated that the embodiments described aboveare not limitative, but only illustrative.

What is claimed is:
 1. A liquid crystal display device comprising: aninsulating substrate; a gate line arranged in a first direction on theinsulating substrate; a plurality of data lines intersecting andinsulated from the gate line and arranged substantially in a seconddirection; a thin film transistor connected to the gate line and atleast one of the data lines, the thin film transistor having an activelayer and source and drain electrodes each at least partiallyoverlapping the active layer; a pixel electrode electrically connectedto the drain electrode; and a storage wiring having first portions eachextending along and overlapping a respective one of the data lines, anda second portion connecting adjacent first portions; wherein the secondportion includes a wiring having a width, the wiring positioned so thatthe entire width of the wiring extends beyond an edge of the pixelelectrode.